JP2003258042A - Method for wire bonding - Google Patents

Method for wire bonding

Info

Publication number
JP2003258042A
JP2003258042A JP2002057597A JP2002057597A JP2003258042A JP 2003258042 A JP2003258042 A JP 2003258042A JP 2002057597 A JP2002057597 A JP 2002057597A JP 2002057597 A JP2002057597 A JP 2002057597A JP 2003258042 A JP2003258042 A JP 2003258042A
Authority
JP
Japan
Prior art keywords
bonding
capillary
wire
ball
electrode pad
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2002057597A
Other languages
Japanese (ja)
Inventor
Takaharu Amano
貴晴 天野
Koichi Mitarai
幸一 御手洗
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Priority to JP2002057597A priority Critical patent/JP2003258042A/en
Publication of JP2003258042A publication Critical patent/JP2003258042A/en
Pending legal-status Critical Current

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    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/74—Apparatus for manufacturing arrangements for connecting or disconnecting semiconductor or solid-state bodies
    • H01L24/78—Apparatus for connecting with wire connectors
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    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
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    • H01L2224/45001—Core members of the connector
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    • H01L2224/451—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45138—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
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    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H01L2224/48465—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
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    • H01L2224/48599—Principal constituent of the connecting portion of the wire connector being Gold (Au)
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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Wire Bonding (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for wire bonding in which the sealability of a connecting point is favorable by preventing a foreign matter such as a squeeze-out or the like generated at a connecting time using an ultrasonic vibration method from occurring and being scattered. <P>SOLUTION: The method for wire bonding comprises a first step of pressing a metal wire 2 on the surface of an electrode pad 5 by bringing a capillary 1 for bonding into contact with the connecting surface of a bonding position by predetermined pressure and vibrating the capillary 1 in a predetermined amplitude; and a second step of pressing the wire 2 on the electrode pad 5 by different pressure from that of the first step by vibrating the capillary 1 in a different amplitude from that of the first step so that in the second step, the pressure applied to the pad 5 is set larger than the pressure of the first step and the vibrating amplitude is smaller than that of the first step. <P>COPYRIGHT: (C)2003,JPO

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、半導体装置の製造
工程において半導体チップの電極パッドとリードフレー
ムのインナーリードとを金属ワイヤで接続するワイヤボ
ンディング方法に関し、特に超音波による金属の塑性変
形効果によって接合する、超音波ボンディング方法に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method for connecting an electrode pad of a semiconductor chip and an inner lead of a lead frame with a metal wire in a manufacturing process of a semiconductor device. The present invention relates to an ultrasonic bonding method for bonding.

【０００２】[0002]

【従来の技術】一般的な半導体製造プロセスにおいて、
電極パッドとボンディングワイヤーとのボンディング表
面電極パッドのボンディング表面、あるいはインナーリ
ード部とボンディングワイヤーとのボンディング表面電
極パッドのボンディング表面には、プロセスの過程にお
いて有機物が付着したり、酸化物が形成される。一方、
最近の高集積化に対応した多層リードフレームを使用し
た半導体製造装置では、多層リードフレームの製造上、
接着剤等の有機材料からの低分子成分等の微量な有機物
の電極パッドあるいはインナーリード部への付着や、大
気などからの酸素による電極パッド表面あるいはインナ
ーリード部表面への表面酸化膜の形成が避けられない上
に、半導体チップ上のボンディングパッド面積が小さく
なっていくことが避けられない。前記有機物が付着した
り酸化物が形成されてしまうと、ワイヤーボンド接続時
に、ボンディング表面とボンディングワイヤーとの接合
面における電極パッドあるいはインナーリード部とボン
ディングワイヤーとの合金形成が阻害される結果、ボン
ディング強度が低下し、ボンディング歩留まりが低下し
てしまうという問題点があった。2. Description of the Related Art In a general semiconductor manufacturing process,
Bonding surface of electrode pad and bonding wire Organic matter adheres to the bonding surface of electrode pad or bonding surface of bonding pad of inner lead portion and bonding wire, or an oxide is formed on the bonding surface of electrode pad. . on the other hand,
In the recent semiconductor manufacturing equipment using a multilayer lead frame corresponding to high integration, in manufacturing the multilayer lead frame,
A small amount of organic substances such as low molecular weight components from organic materials such as adhesives may adhere to the electrode pad or the inner lead part, or surface oxide film may be formed on the electrode pad surface or the inner lead part surface by oxygen from the atmosphere. In addition to being inevitable, it is inevitable that the bonding pad area on the semiconductor chip becomes smaller. When the organic matter is adhered or an oxide is formed, the formation of an alloy between the electrode pad or the inner lead portion and the bonding wire at the bonding surface between the bonding surface and the bonding wire is hindered during wire bond connection, resulting in bonding. There is a problem that the strength is lowered and the bonding yield is lowered.

【０００３】係る問題点を解決するためにボンディング
用のツールとは全く異なるボンディング表面残渣除去の
ためのツールを用いて突起部を所定の圧力で押し付け
て、接触させた状態ですり合わせるスクラブ動作を予め
行って当該接合表面上の異物を除去するボンディング表
面残渣除去工程を有する装置もあるが、装置が高価であ
ると共に、ボンディング表面残渣除去工程が必要な為
に、ボンディング時間が長くなる。In order to solve such a problem, a scrubbing operation is carried out by pressing a protrusion with a predetermined pressure using a tool for removing a residue on a bonding surface, which is completely different from a bonding tool, and contacting each other. Although there is an apparatus that has a bonding surface residue removing step that removes foreign matter on the bonding surface in advance, the apparatus is expensive and the bonding time becomes long because the bonding surface residue removing step is required.

【０００４】一方、近年のボンディング方法には超音波
振動式と呼ばれる接合方法がある。該超音波を用いる接
合方法では針状に形成された細径のキャピラリを用い、
このキャピラリを超音波発振源から導出された超音波ホ
ーンの先端に保持することで、上記キャピラリに超音波
振動を伝達するようにしている。前記の超音波振動式の
接合方法では、前記スクラブ動作をボンディングの際に
行なう。係る方法では超音波振動を印加する際にボンデ
ィング位置接合表面と金属ワイヤが接触して擦れ合い、
その結果スクイズアウトと呼ばれる鉋屑状のチリが発生
する。その結果、前記スクイズアウトなどの異物が飛散
して半導体に付着した場合、半導体の動作不良などが発
生し、信頼性を著しく低減させるいう問題点があった。On the other hand, as a recent bonding method, there is a bonding method called ultrasonic vibration type. In the joining method using the ultrasonic wave, a needle-shaped thin capillary is used,
By holding this capillary at the tip of the ultrasonic horn led out from the ultrasonic oscillating source, the ultrasonic vibration is transmitted to the capillary. In the ultrasonic vibration type joining method, the scrubbing operation is performed at the time of bonding. In such a method, when the ultrasonic vibration is applied, the bonding position bonding surface and the metal wire contact and rub against each other,
As a result, squeeze-out dust like dust is generated. As a result, when the foreign matter such as the squeeze-out scatters and adheres to the semiconductor, a malfunction of the semiconductor occurs and the reliability is remarkably reduced.

【０００５】又、ボンディング位置にこの異物が不純物
として混入した場合、このような不純物が混入した状態
でワイヤーボンド接続を行ってしまうと、ボンディング
表面とボンディングワイヤーとの接合面における電極パ
ッドあるいはインナーリード部とボンディングワイヤー
との合金形成が阻害される結果、ボンディング強度が低
下し、ボンディング歩留まりが低下してしまうという問
題点もあった。Further, when the foreign matter is mixed in as an impurity at the bonding position, if the wire bond connection is performed in the state where such an impurity is mixed, an electrode pad or an inner lead on the bonding surface between the bonding surface and the bonding wire is formed. There is also a problem that as a result of the formation of an alloy between the bonding portion and the bonding wire being hindered, the bonding strength is reduced and the bonding yield is reduced.

【０００６】又、上記キャピラリは、上述したように超
音波ホーンを介して支持されいるので、この超音波ホー
ンに撓み等が生じることにより面検出に時間的な遅れが
生じるということがある。また、接合を高速で行おうと
すると、第１のボンディング点と第２のボンディング点
との間に形成されるワイヤが最適なループ形状にならな
いということがある。すなわち、ループ形状の成形は、
上記キャピラリからワイヤを繰り出しつつ行うので、こ
のキャピラリ内における上記ワイヤの挿通抵抗が問題と
なる。Further, since the capillaries are supported via the ultrasonic horn as described above, there is a case where surface detection is delayed due to bending of the ultrasonic horn. In addition, if the bonding is attempted at a high speed, the wire formed between the first bonding point and the second bonding point may not have an optimum loop shape. That is, the loop-shaped molding is
Since the wire is fed out from the capillary, the insertion resistance of the wire in the capillary becomes a problem.

【０００７】更に又、上述した接合を繰り返すと、上記
スクイズアウトやワイヤの「かす」等によってキャピラ
リの内部が汚れ、これが挿通抵抗の増大につながるとい
うことがある。すなわち、このような「かす」がキャピ
ラリ内に付着している状態で、上記キャピラリを高速駆
動しようとすると、上記ワイヤがキャピラリ内でひっか
かり、適当なループ形状が得られなかったりワイヤが切
れたりするということがある。このため、ループ形状を
良好にするために第１のボンディング点から第２のボン
ディング点までのキャピラリの移動を高速で行うことに
は限界があり、その分ワイヤボンディングに時間がかか
っているということがある。Furthermore, when the above-mentioned joining is repeated, the inside of the capillary may be contaminated by the squeezeout or the wire "smear", which may increase the insertion resistance. That is, when trying to drive the capillary at a high speed in a state in which such "dust" is attached to the capillary, the wire is caught in the capillary, and an appropriate loop shape cannot be obtained or the wire is cut. There is a thing. Therefore, there is a limit to moving the capillary from the first bonding point to the second bonding point at high speed in order to improve the loop shape, and it takes time to wire-bond accordingly. There is.

【０００８】前記問題点を解決する前記超音波振動式の
ボンディング方法として、特開平８−１８１１７５号公
報に開示されている「ワイヤボンディング方法」があ
る。係る発明は、キャピラリ内にワイヤを挿通し、該キ
ャピラリの押圧面で上記ワイヤを第１のボンディング点
と第２のボンディング点とに順に押し付け接合する際、
上記第１のボンディング点に対するワイヤの押し付け前
から上記キャピラリに超音波振動を与え、少なくとも第
２のボンディング点に対するワイヤの接合が終了するま
で上記ワイヤに超音波振動を印加し続けるボンディング
方法である。即ち、前記発明は、挿通抵抗の増大を防止
してボンディング速度の向上と、第１のボンディング点
と第２のボンディング点とのワイヤのループ形状を良好
にすることを目的としてなされた発明である。発明の問
題点の理解を容易にするために、その動作を図５、図６
及び図７を用いて以下に説明する。As the ultrasonic vibration type bonding method for solving the above problems, there is a "wire bonding method" disclosed in Japanese Patent Laid-Open No. 8-181175. According to the invention, when the wire is inserted into the capillary and the wire is pressed by the pressing surface of the capillary to the first bonding point and the second bonding point in order,
This is a bonding method in which ultrasonic vibration is applied to the capillary before the wire is pressed against the first bonding point, and ultrasonic vibration is continuously applied to the wire at least until the bonding of the wire to the second bonding point is completed. That is, the invention is made for the purpose of preventing an increase in insertion resistance, improving a bonding speed, and improving a wire loop shape between the first bonding point and the second bonding point. . In order to facilitate understanding of the problems of the invention, the operation thereof will be described with reference to FIGS.
And FIG. 7 will be described below.

【０００９】図５は、従来のボンディング装置の説明図
である。半導体チップ４の表面に形成されている電極パ
ッド５及びインナーリード部６の各々にキャピラリ１を
接触させワイヤボンディングを行なう装置である。キャ
ピラリ１の先端からクランパ７を介して金属ワイヤ２を
突出させ、該金属ワイヤ２の先端部に球状のボールを形
成し、第１ボンディングである電極パッド５への接続と
第２ボンディングであるインナーリード部６への接続を
行なう。FIG. 5 is an explanatory view of a conventional bonding apparatus. In this device, the capillary 1 is brought into contact with each of the electrode pad 5 and the inner lead portion 6 formed on the surface of the semiconductor chip 4 to perform wire bonding. The metal wire 2 is projected from the tip of the capillary 1 through the clamper 7, a spherical ball is formed at the tip of the metal wire 2, and the connection to the electrode pad 5 which is the first bonding and the inner bonding which is the second bonding. Connection to the lead portion 6 is made.

【００１０】図６はキャピラリ１の動作を説明する図で
あって、図６（ａ）は、前記キャピラリ１の上下方向の
動作を時間との関係で示すものである。キャピラリ１
は、図６（ａ）に示すように、上記電極パッド５の直上
約０．２〜０．３ｍｍの高さ（点Ａで示す）まで高速で
下降駆動され、それ以後は速度を落として等速で下降駆
動される。一方、図６（ｂ）は、キャピラリ１に振動を
与える、図示していない超音波振動子に対する電圧印加
のゲイン切替により発生する超音波振動の振幅を示す図
であり、図６（ｃ）は、前記ゲイン切替を示す図であ
る。この超音波振動の振幅は、前記超音波振動子に設け
られた図示しないセンサあるいはこの超音波振動子に接
続された図示しない超音波発振器に設けられた図示しな
いセンサにより検出するようにする。FIG. 6 is a diagram for explaining the operation of the capillary 1, and FIG. 6 (a) shows the vertical operation of the capillary 1 in relation to time. Capillary 1
6 is driven at a high speed to a height of about 0.2 to 0.3 mm (shown by point A) immediately above the electrode pad 5 as shown in FIG. Driven downward at high speed. On the other hand, FIG. 6B is a diagram showing the amplitude of the ultrasonic vibration generated by the gain switching of the voltage application to the ultrasonic vibrator (not shown) that gives vibration to the capillary 1, and FIG. FIG. 4 is a diagram showing the gain switching. The amplitude of this ultrasonic vibration is detected by a sensor (not shown) provided on the ultrasonic oscillator or a sensor (not shown) provided on an ultrasonic oscillator (not shown) connected to the ultrasonic oscillator.

【００１１】前記図６（ｂ）および（ｃ）に示すよう
に、上記キャピラリ１が点Ａに達したならば、第１のゲ
インＧ１（超音波振動がない状態）が第２のゲインＧ２
に切替えられ、ボール８は、半導体チップ４の電極パッ
ド５に押し付けられる前から超音波域で振幅ＡＶ９で振
動することとなる。図６（ａ）に示す点Ｂの高さでボー
ル８と半導体チップ４の電極パッド５とが当接される。
この点Ｂ以後、上記ボール８は電極パッド５への押し付
けを開始され、当接した部位から接合されていく。ボー
ル８が電極パッド５に押し付けられ、接合が開始される
と、図６（ｂ）に示すように上記超音波振動の振幅（波
形）が振幅ＡＶ９から振幅ＡＶ１０に減少する。そし
て、図示しない制御部は、この信号に基づいて、図６
（ｃ）に示すように第２のゲイン切替を行い、第２のゲ
インＧ２は第３のゲインＧ３に切替えられ超音波振動の
出力を上げる。As shown in FIGS. 6 (b) and 6 (c), when the capillary 1 reaches the point A, the first gain G1 (the state without ultrasonic vibration) is the second gain G2.
Then, the ball 8 vibrates with an amplitude AV9 in the ultrasonic range before being pressed against the electrode pad 5 of the semiconductor chip 4. The ball 8 and the electrode pad 5 of the semiconductor chip 4 are brought into contact with each other at the height of a point B shown in FIG.
After this point B, the ball 8 is started to be pressed against the electrode pad 5, and is joined from the abutted portion. When the ball 8 is pressed against the electrode pad 5 and the bonding is started, the amplitude (waveform) of the ultrasonic vibration decreases from the amplitude AV9 to the amplitude AV10 as shown in FIG. 6B. Then, the control unit not shown in FIG.
As shown in (c), the second gain switching is performed, the second gain G2 is switched to the third gain G3, and the output of ultrasonic vibration is increased.

【００１２】超音波による接合を開始した後、上記キャ
ピラリ１は若干量ではあるが、下降を続け（図６（ａ）
Ｂ〜Ｃ間で示す部位）上記ボール８が押し潰されて行
く。なお、ボール８は、押し潰されることによって、上
記電極パッド５との接触面積を次第に広げていく。前記
図６（ａ）Ｂ〜Ｃ間で示す間、キャピラリ１の圧力とボ
ール８からの反発力によりボール８には圧力Ｐ１が加わ
り、またこの間では図６（ｂ）に示すように点Ｂでゲイ
ンを第３のゲインＧ３に切替えてもその振幅ＡＶ１０は
小さい。ボール８が押し潰されたならば（図６（ａ）に
示す点Ｃに相当）上記キャピラリ１の下降は停止し、図
にＣ〜Ｄ間に示すように高さ一定の状態で保持される。
この間も、上記キャピラリ１は上記ボール８に超音波振
動を印加しつづけ、このボール８と電極パッド５との接
合を行う。After the ultrasonic bonding is started, the capillary 1 continues to descend, albeit with a slight amount (see FIG. 6A).
(Part indicated between B and C) The ball 8 is crushed. The ball 8 gradually expands the contact area with the electrode pad 5 by being crushed. During the period shown in FIGS. 6A to 6C, the pressure P1 is applied to the ball 8 due to the pressure of the capillary 1 and the repulsive force from the ball 8, and during this period, at the point B as shown in FIG. 6B. Even if the gain is switched to the third gain G3, the amplitude AV10 is small. When the ball 8 is crushed (corresponding to the point C shown in FIG. 6A), the lowering of the capillary 1 is stopped and is held at a constant height as shown between C and D in the figure. .
During this time, the capillary 1 continues to apply ultrasonic vibration to the ball 8 to bond the ball 8 and the electrode pad 5 together.

【００１３】点Ｂでゲインを第３のゲインＧ３に切替え
た効果が点Ｃになると現れて、振幅ＡＶ１０が増加して
振幅ＡＶ１１になる。そしてボール８に圧力Ｐ１を加え
てから一定時間が経過し、上記ボール８と電極パッド５
とが完全に接合されたならば、上記キャピラリ１は上昇
駆動される（点Ｄに相当）。キャピラリ１が上昇駆動さ
れたならば、ボール８に印加される圧力が低下して上記
超音波振動子を駆動する図示しない超音波発振器の負荷
が軽減し、超音波振動の振幅（波形）は更に増加して振
幅ＡＶ１２になるから、これに基づいて上記超音波振動
子に印加する第３のゲイン切替がなされ、第２のゲイン
Ｇ２の大きさに戻される。以上の如く、ボール８が電極
パッド５に押し付けられ、接合が開始されると、図６
（ａ）Ｂ〜Ｃ間で示す間、キャピラリ１の振動振幅は振
幅ＡＶ１０に減少する。また、キャピラリ１の下降が停
止している図６（ａ）Ｃ〜Ｄ間ではキャピラリ１の振動
振幅はＡＶ１１に増加する。The effect of switching the gain to the third gain G3 at the point B appears at the point C, and the amplitude AV10 increases to the amplitude AV11. Then, after a certain period of time has passed since the pressure P1 was applied to the ball 8, the ball 8 and the electrode pad 5
When and are completely joined, the capillary 1 is driven upward (corresponding to point D). When the capillary 1 is driven upward, the pressure applied to the ball 8 is reduced, the load of the ultrasonic oscillator (not shown) that drives the ultrasonic vibrator is reduced, and the amplitude (waveform) of ultrasonic vibration is further increased. Since the amplitude is increased to AV12, the third gain applied to the ultrasonic transducer is switched based on this, and the magnitude is returned to the magnitude of the second gain G2. As described above, when the ball 8 is pressed against the electrode pad 5 and the bonding is started, as shown in FIG.
(A) During the period shown between B and C, the vibration amplitude of the capillary 1 decreases to the amplitude AV10. In addition, the vibration amplitude of the capillary 1 increases to AV11 between C and D in FIG. 6A where the lowering of the capillary 1 is stopped.

【００１４】図７は、前述のワイヤボンディング方法に
おける接合部の接合状態を説明する図であって、図７
（ａ）は前記ボール８が電極パッド５に圧着された時の
圧着方向の断面図、図７（ｂ）と図７（ｃ）は、ボール
８と電極パッド５の接合点における、ボール８への圧力
方向と接合面方向の圧力分布を、それぞれ説明する図で
ある。FIG. 7 is a diagram for explaining the bonding state of the bonding portion in the wire bonding method described above.
7A is a cross-sectional view in the crimping direction when the ball 8 is crimped to the electrode pad 5, and FIGS. 7B and 7C show the ball 8 at the joining point between the ball 8 and the electrode pad 5. It is a figure which respectively explains the pressure distribution of the pressure direction of and the joint surface direction.

【００１５】半導体素子４には電極パッド５が形成され
ていて、該電極パッド５にはその先端がボール状になっ
ている金属ワイヤ２がキャピラリ１により前記ボール８
が所定の圧力で図７（ａ）の如く圧着される。その結
果、キャピラリ１の形状により、前記ボール８に印加さ
れる圧力が異なる箇所が図７（ｂ）、図７（ｃ）に示す
ように発生する。即ち、キャピラリ１の先端の形状によ
りボール８と電極パッド５の接合点における圧力は、キ
ャピラリ１の先端により圧着される中心から外れた部分
８ｂが最も圧力が高く、その周辺部分８ａと中心部分８
ｃは圧力が低くなる。その結果、中心から外れた部分８
ｂと、周辺部分８ａ及び中心部分８ｃとの密着力は異な
り、周辺部分８ａ及び中心部分８ｃは、密着力が中心か
ら外れた部分８ｂよりも低くなる。An electrode pad 5 is formed on the semiconductor element 4, and a metal wire 2 having a ball-shaped tip is formed on the electrode pad 5 by means of a capillary 1 to form the ball 8.
Is pressed with a predetermined pressure as shown in FIG. As a result, a portion where the pressure applied to the ball 8 differs depending on the shape of the capillary 1 is generated as shown in FIGS. 7B and 7C. That is, due to the shape of the tip of the capillary 1, the pressure at the junction between the ball 8 and the electrode pad 5 is highest at the portion 8b decentered from the center of the capillary 1 which is crimped, and the peripheral portion 8a and the central portion 8 thereof.
c has a low pressure. As a result, the off-center part 8
Adhesion between the peripheral portion 8a and the central portion 8c is different from that of the peripheral portion 8a.

【００１６】[0016]

【発明が解決しようとする課題】前述の特開平８−１８
１１７５号公報に開示されている「ワイヤボンディング
方法」では、図７に示したように、ボール８と電極パッ
ド５の接合点では、キャピラリ１の真下になる箇所での
接合状態がよく、ボール８と電極パッド５との密着力が
強い。しかし、それ以外の周辺８ａと中心８ｃではキャ
ピラリ１からの圧力が小さく接合状態が悪い。この結
果、ボール８の外周部８ａと中心部８ｃとでは、ボール
８と電極パッド５との密着力が弱い。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the “wire bonding method” disclosed in Japanese Patent No. 1175, as shown in FIG. 7, at the bonding point between the ball 8 and the electrode pad 5, the bonding state is good at a position directly below the capillary 1 and the ball 8 And the electrode pad 5 have strong adhesion. However, the pressure from the capillary 1 is small and the bonding state is poor in the other peripheral portions 8a and the center 8c. As a result, the adhesion between the ball 8 and the electrode pad 5 is weak between the outer peripheral portion 8a and the central portion 8c of the ball 8.

【００１７】一方、前記ボール８と電極パッド５の接合
点においては、半導体素子４や電極パッド５の温度変化
などにより応力が発生する。その応力は前記ボール８の
外周部８ａに集中する。かかる応力の発生によりボール
８と電極パッド５との密着力が強いキャピラリ１の真下
になる箇所８ｂにクラックが発生すると、ボール８全体
の密着力は急激に減少して、半導体素子４の動作の信頼
性が著しく低下する問題点がある。また、ボール８が電
極パッド５に押し付けられ、接合が開始されると、図６
（ａ）Ｂ〜Ｃ間で示す間、振幅ＡＶ１０に減少する。そ
して、キャピラリ１の下降が停止している図６（ａ）Ｃ
〜Ｄ間では振幅はＡＶ１１に増加する。その結果、ボン
ディング速度の向上と、第１のボンディング点と第２の
ボンディング点とのワイヤのループ形状を良好にするこ
とはできるが、図６（ａ）Ｂ〜Ｃ間で示す間、ボンディ
ング位置接合表面と金属ワイヤが接触して擦れ合って発
生する、スクイズアウトと呼ばれる鉋屑状のチリの発生
防止はできない。On the other hand, at the junction between the ball 8 and the electrode pad 5, stress is generated due to temperature changes of the semiconductor element 4 and the electrode pad 5. The stress is concentrated on the outer peripheral portion 8a of the ball 8. When a crack is generated in the portion 8b directly below the capillary 1 where the adhesive force between the ball 8 and the electrode pad 5 is strong due to the generation of such stress, the adhesive force of the ball 8 as a whole suddenly decreases, and the operation of the semiconductor element 4 is reduced. There is a problem that the reliability is significantly reduced. Further, when the ball 8 is pressed against the electrode pad 5 and the bonding is started, as shown in FIG.
(A) The amplitude decreases to AV10 during the period shown between B and C. The lowering of the capillary 1 is stopped in FIG. 6 (a) C.
The amplitude increases to AV11 between D. As a result, although the bonding speed can be improved and the wire loop shape between the first bonding point and the second bonding point can be improved, the bonding position can be increased during the period shown in FIGS. 6A to 6C. It is not possible to prevent the generation of squeezeout-like dust, which is caused by the contact between the bonding surface and the metal wire and rubbing against each other.

【００１８】更にまた、図６（ａ）Ｃ〜Ｄ間での振幅は
ＡＶ１１に増加し、前記スクイズアウトなどの異物がキ
ャピラリの振動振幅の増加により飛散して半導体に付着
して、半導体の動作不良などが発生し、信頼性を著しく
低減させるいう問題点があった。更に、図６（ａ）Ｂ〜
Ｃ間で示す間はキャピラリの振動振幅は振幅ＡＶ１０に
減少しているので、接合表面と金属ワイヤとの密着力が
強い接合面が小さく、その小さい接合面の周辺に前記ス
クイズアウトなどの異物が発生してい、図６（ａ）Ｃ〜
Ｄ間では、前記接合表面と金属ワイヤとの密着力の強い
接合面が小さいまま、金属ワイヤを接合してしまう問題
点があった。Furthermore, the amplitude between C and D in FIG. 6 (a) increases to AV11, and the foreign matter such as the squeeze out scatters due to the increase in the vibration amplitude of the capillary and adheres to the semiconductor, thereby operating the semiconductor. There has been a problem that defects are generated and the reliability is significantly reduced. Further, FIG.
Since the vibration amplitude of the capillary is reduced to the amplitude AV10 during the period indicated by C, the joint surface where the adhesive force between the joint surface and the metal wire is strong is small, and foreign matter such as the squeezeout is present around the small joint surface. Has occurred, and FIG.
Between D, there is a problem that the metal wire is bonded while the bonding surface having strong adhesion between the bonding surface and the metal wire is small.

【００１９】前記問題点が残されているのは、ボンディ
ング工程において、挿通抵抗の増大を防止してボンディ
ング速度の向上と、第１のボンディング点と第２のボン
ディング点とのワイヤのループ形状を良好にするため
に、ワイヤに超音波振動を印加し続け、その振動振幅の
出力のみを調整し、ボンディング時の圧力を考慮してい
ないボンディング方法に起因するものである。The above-mentioned problems remain, in the bonding process, in order to prevent an increase in insertion resistance, improve the bonding speed, and to improve the wire loop shape between the first bonding point and the second bonding point. This is due to a bonding method in which ultrasonic vibration is continuously applied to the wire, only the output of the vibration amplitude is adjusted, and the pressure at the time of bonding is not taken into consideration in order to improve the quality.

【００２０】本発明は、係る問題を解決して超音波振動
式の接合時に発生するスクイズアウトなどの異物の発生
を抑制すると共に、発生した前記異物の飛散を防止し、
接合点の密着度の良好なワイヤボンディング方法を提供
し、合わせてこの方法により製造された半導体の信頼性
を向上することを目的としてなされたものである。The present invention solves the above problems and suppresses the generation of foreign matter such as squeezeout that occurs during ultrasonic vibration type joining, and prevents the generated foreign matter from scattering.
The present invention has been made for the purpose of providing a wire bonding method having good adhesion at a bonding point and also improving the reliability of a semiconductor manufactured by this method.

【００２１】[0021]

【課題を解決するための手段】本願発明は、上記目的を
達成するために、ボンディング工程に金属ワイヤの圧力
と振動振幅とをそれぞれ制御する工程を設けたワイヤボ
ンディング方法である。更に詳しくは、請求項１に記載
されたワイヤボンディング方法では、半導体チップの電
極パッドと前記半導体チップを載置するリードフレーム
のインナーリード部とを金属ワイヤを用いて接続するワ
イヤボンディング方法において、ボンディング位置の接
合表面にボンディング用のツールを所定の圧力で接触さ
せて金属ワイヤを所定の振幅で振動させて金属ワイヤを
押圧する第１工程と、該第１工程の後に前記第１の工程
より大きい圧力で前記金属ワイヤを押圧する第２工程と
を有することを特徴とする。In order to achieve the above object, the present invention is a wire bonding method in which a step of controlling the pressure and vibration amplitude of a metal wire is provided in the bonding step. More specifically, the wire bonding method according to claim 1, wherein the electrode pad of the semiconductor chip and the inner lead portion of the lead frame on which the semiconductor chip is mounted are connected using a metal wire. A first step in which a bonding tool is brought into contact with the bonding surface at a position at a predetermined pressure to vibrate the metal wire at a predetermined amplitude to press the metal wire, and after the first step, the first step is larger than the first step. A second step of pressing the metal wire with pressure.

【００２２】又、請求項２に記載された発明は、請求項
１に記載のワイヤボンディング方法において、前記第２
工程における金属ワイヤの振動振幅を、前記第１工程に
おける金属ワイヤの振動振幅より小さくすることを特徴
とする。According to a second aspect of the present invention, in the wire bonding method according to the first aspect, the second
The vibration amplitude of the metal wire in the step is smaller than the vibration amplitude of the metal wire in the first step.

【００２３】さらに、請求項３に記載された発明は、請
求項１に記載のワイヤボンディング方法において、前記
金属ワイヤの振動振幅の変化は、超音波振動子駆動装置
により前記超音波振動子に印加する印加電圧を切り替え
てボンディング用のツールを振動することを特徴とす
る。Further, in the invention described in claim 3, in the wire bonding method according to claim 1, a change in the vibration amplitude of the metal wire is applied to the ultrasonic vibrator by an ultrasonic vibrator driving device. The application voltage is changed to vibrate the bonding tool.

【００２４】本発明のワイヤボンディング方法によれ
ば、ボンディング用のツール（キャピラリ）の圧力と振
動振幅とを変更する第１工程と第２工程とを設けたこと
により、従来問題であったボール８と電極パッド５との
密着力が強い箇所を、前記キャピラリ１の真下になる箇
所８ｂからボール８の中心部８ｃにすることができる。
また、前記キャピラリ１の振動、又は所定の圧力で押圧
されたボール８の振動によって発生するスクイズアウト
の抑制ができる。そして、前記第２工程において、接合
表面に印加される圧力は前記第１工程における圧力より
大きく、好ましくは更にその振動振幅は前記第１工程に
おける振動振幅より小さくする。これにより、前記第１
工程で発生したスクイズアウトを第２工程によりボール
８の外周部８ａで押さえ込む。その結果、従来問題であ
ったスクイズアウトなどの異物が飛散して半導体に付着
した場合、半導体の動作不良などが発生し、信頼性を著
しく低減させるいう問題点をなくすことができる。According to the wire bonding method of the present invention, by providing the first step and the second step of changing the pressure and the vibration amplitude of the bonding tool (capillary), the ball 8 which has been a problem in the prior art. It is possible to set the portion having a strong adhesion between the electrode pad 5 and the electrode pad 5 from the portion 8b directly below the capillary 1 to the central portion 8c of the ball 8.
Further, squeeze-out that occurs due to the vibration of the capillary 1 or the vibration of the ball 8 pressed by a predetermined pressure can be suppressed. Then, in the second step, the pressure applied to the bonding surface is higher than the pressure in the first step, and preferably the vibration amplitude thereof is smaller than the vibration amplitude in the first step. Thereby, the first
The squeezeout generated in the process is pressed down by the outer peripheral portion 8a of the ball 8 in the second process. As a result, when a foreign matter such as a squeeze-out is scattered and adheres to the semiconductor, which is a conventional problem, a malfunction of the semiconductor occurs and the reliability is significantly reduced.

【００２５】[0025]

【発明の実施の形態】以下、本発明のワイヤボンディン
グ方法の一実施例について図面を参照して説明する。図
１は、ワイヤボンディング方法の工程を示す概略工程図
であって、その工程は、図１の符号乃至に示す順序
である。図２は、図１の工程及びにおけるボンディ
ング点における接合状態を拡大して示す図であって、図
２（ａ）、図２（ｂ）は、それぞれ図１の工程及び工
程に対応した図である。図３は接合部の接合状態を説
明する図であって、図３（ａ）は前記ボール８が電極パ
ッド５に圧着された時の圧着方向の断面図、図３（ｂ）
はボール８と電極パッド５の接合点に置ける断面図、図
３（ｃ）は図３（ａ）でのボール８の圧力分布を説明す
る図である。BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the wire bonding method of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic process drawing showing the steps of the wire bonding method, and the steps are in the order shown by the reference numerals in FIG. FIG. 2 is an enlarged view showing a bonding state at a bonding point in the step of FIG. 1, and FIGS. 2A and 2B are views corresponding to the step of FIG. 1 and the step, respectively. is there. 3A and 3B are views for explaining the bonding state of the bonding portion, and FIG. 3A is a sectional view in the pressure bonding direction when the ball 8 is pressure bonded to the electrode pad 5, FIG. 3B.
FIG. 3C is a cross-sectional view at the junction between the ball 8 and the electrode pad 5, and FIG. 3C is a diagram illustrating the pressure distribution of the ball 8 in FIG. 3A.

【００２６】図４はキャピラリ１の加圧制御および超音
波振動の振幅制御を示す図であって、図４（ａ）、図４
（ｂ）、図４（ｃ）は、それぞれ加圧制御と振幅制御及
びキャピラリ１の位置を示す図であって、図４（ａ）
は、超音波振動子駆動装置内に設けられた図示しない超
音波振動子に印加する加圧制御における圧力の切替を示
す図である。また、図４（ｂ）は、振幅制御における超
音波振動の振幅を示すグラフであり、図４（ｃ）は、こ
のキャピラリ１の上下方向の動作ｔ時間との関係で示す
図である。上記キャピラリ１は、この図４（ｃ）に示す
ように、上記半導体チップ４の電極パッドの直上点Ａま
で下降駆動され、それ以後は速度を落として下降駆動さ
れる。なお、図４（ａ）、図４（ｂ）、図４（ｃ）は、
それぞれ時間軸上で同一時刻には同一符号を付してあ
り、また図４（ｂ）の超音波振動周波数は、通常のワイ
ヤボンディング装置に用いられる超音波周波数である。FIG. 4 is a diagram showing pressurization control of the capillary 1 and amplitude control of ultrasonic vibration.
4 (b) and 4 (c) are diagrams showing the pressurization control, the amplitude control, and the position of the capillary 1, respectively.
FIG. 6 is a diagram showing pressure switching in pressurization control applied to an ultrasonic transducer (not shown) provided in the ultrasonic transducer driving device. 4 (b) is a graph showing the amplitude of ultrasonic vibration in amplitude control, and FIG. 4 (c) is a diagram showing the relationship with the vertical operation time t of the capillary 1. As shown in FIG. 4 (c), the capillary 1 is driven downward to a point A directly above the electrode pad of the semiconductor chip 4, and thereafter, is driven at a reduced speed. 4 (a), 4 (b) and 4 (c)
The same symbol is given to the same time on each time axis, and the ultrasonic vibration frequency in FIG. 4B is an ultrasonic frequency used in a normal wire bonding apparatus.

【００２７】前記各図において、図５と同一部分につい
ては同一符号を付して説明する。まず、工程の図（図
１）を参照し、ワイヤボンディング装置の構成について
簡単に説明する。工程の図（図１）において、ワイヤ
ボンディング動作を行うキャピラリ１は、先端が細径に
形成されてなる針状をなし、内部には金属ワイヤ（例え
ば金ワイヤ）２が挿通される挿通孔１ａが上下方向全長
に亘って形成されている。前記キャピラリ１は、図示し
ていない周知の超音波ホーンの先端に軸線を略垂直にし
た状態で保持されている。そして、前記超音波ホーンの
他端側は、図示していない周知の超音波振動子駆動装置
に接続されており、超音波振動子に印加する印加電圧が
切り替えられることによりその振動振幅が変化される。
したがって、前記超音波振動子に電圧を印加し、超音波
振動を発振させることで、上記超音波ホーンを介して、
上記キャピラリ１に超音波振動が伝達され、その内部に
挿通されている金属ワイヤ２が振動されるようになって
いる。また、前記超音波振動子駆動装置は図示していな
い回動軸（水平軸）によって揺動自在に設けられてお
り、該回胴軸が揺動することで、上記キャピラリ１を上
下させることができるように構成されている。In each of the above-mentioned drawings, the same parts as those in FIG. First, the configuration of the wire bonding apparatus will be briefly described with reference to the process diagram (FIG. 1). In the process diagram (FIG. 1), a capillary 1 for performing a wire bonding operation has a needle-like shape with a tip having a small diameter, and a metal wire (for example, a gold wire) 2 is inserted through the insertion hole 1a. Are formed over the entire length in the vertical direction. The capillary 1 is held at the tip of a well-known ultrasonic horn (not shown) with its axis substantially vertical. The other end of the ultrasonic horn is connected to a well-known ultrasonic vibrator driving device (not shown), and its vibration amplitude is changed by switching the applied voltage applied to the ultrasonic vibrator. It
Therefore, by applying a voltage to the ultrasonic transducer to oscillate the ultrasonic vibration, through the ultrasonic horn,
Ultrasonic vibration is transmitted to the capillary 1 so that the metal wire 2 inserted therein is vibrated. Further, the ultrasonic transducer driving device is swingably provided by a rotary shaft (horizontal shaft) (not shown), and the capillary 1 can be moved up and down by swinging the rotating body shaft. It is configured to be able to.

【００２８】なお、前記回動軸は図示しないモータに連
結され、前記モータが作動することで、上記キャピラリ
１は所定の速度、加速度、圧力で上下駆動されるように
なっている。さらに、上記キャピラリ１は図示していな
いＸＹテーブルが作動することにより水平方向にも駆動
位置決めができるようになっている。前記キャピラリ１
の横には電気トーチ９が設けられていて、該電気トーチ
９は放電により上記金属ワイヤ２を加熱し、後述するよ
うにして上記金属ワイヤ２の先端部を溶融させて、そこ
にボール状のボール８が形成される。一方、プリント基
板１０は、図示していない上面は略平坦に形成されてい
る周知のボンディングステージに保持固定されている。
なお、前記ボンディングステージ内には、図示しないヒ
ータが埋設されており、ボンディングを行う際には、所
定の温度に昇温制御されるようになっている。前記プリ
ント基板１０上には半導体チップ４が周知のダイボンデ
ィングにより搭載されている。また、上記プリント基板
１０の上面と上記半導体チップ４の上面には、それぞれ
電極パッド１１、電極パッド５が形成されている。The rotary shaft is connected to a motor (not shown), and when the motor is operated, the capillary 1 is vertically driven at a predetermined speed, acceleration and pressure. Further, the capillary 1 can be driven and positioned in the horizontal direction by operating an XY table (not shown). The capillary 1
An electric torch 9 is provided on the side of the electric torch 9, and the electric torch 9 heats the metal wire 2 by electric discharge, melts the tip of the metal wire 2 as described later, and forms a ball-like shape there. The ball 8 is formed. On the other hand, the printed circuit board 10 is held and fixed on a well-known bonding stage whose upper surface (not shown) is formed to be substantially flat.
A heater (not shown) is embedded in the bonding stage so that the temperature is controlled to a predetermined temperature when bonding is performed. A semiconductor chip 4 is mounted on the printed board 10 by known die bonding. Further, an electrode pad 11 and an electrode pad 5 are formed on the upper surface of the printed board 10 and the upper surface of the semiconductor chip 4, respectively.

【００２９】このワイヤボンディング装置は、上記キャ
ピラリ１を、順次上記半導体チップ４の電極パッド５
（第１のボンディング点）とプリント基板１０の電極パ
ッド１１（第２のボンディング点）とに対向させ、これ
らの間を、上記金属ワイヤ２を用いて接続するものであ
る。なお、接続に用いられる金属ワイヤ２は、上記キャ
ピラリ１の上方に設けられた図示しないワイヤスプール
から導出され、上記キャピラリ１の挿通孔１ａに上下方
向に挿通された後、先端部が上記キャピラリ１の下端面
から所定寸法だけ露出されていて、前述のように電気ト
ーチ９により、金属ワイヤ２の先端部に球状のボール８
が形成されている。また、上記キャピラリ１の上方に
は、該キャピラリ１と共に上下するワイヤクランパ７が
設けられている。該ワイヤクランパ７は、必要に応じて
作動し、前記金属ワイヤ２を保持または開放するように
なっている。In this wire bonding apparatus, the capillaries 1 are sequentially connected to the electrode pads 5 of the semiconductor chip 4.
The (first bonding point) and the electrode pad 11 (second bonding point) of the printed board 10 are opposed to each other, and the metal wires 2 are used to connect them. The metal wire 2 used for the connection is drawn out from a wire spool (not shown) provided above the capillary 1 and is vertically inserted into the insertion hole 1a of the capillary 1, and then the tip portion is connected to the capillary 1. A predetermined size is exposed from the lower end surface of the metal wire 2, and the spherical ball 8 is attached to the tip of the metal wire 2 by the electric torch 9 as described above.
Are formed. A wire clamper 7 that moves up and down together with the capillary 1 is provided above the capillary 1. The wire clamper 7 is operated as required to hold or release the metal wire 2.

【００３０】次に、このキャピラリ１および金属ワイヤ
２を用いたワイヤボンディングの工程について、図１、
図２、図３及び図４を参照して説明する。まず、前記キ
ャピラリ１は、図示していないＸＹテーブルが作動する
ことで半導体チップ４における所定の電極パッド５（第
１のボンディング点）の上方に対向位置決めされる。つ
いで、電気トーチ９が作動し、放電による加熱により上
記金属ワイヤ２の先端部を溶融させ、この金属ワイヤ２
の先端部に球状のボール８を形成する。ボール８が形成
されたならば、上記キャピラリ１は所定量だけ下降駆動
され、図１の工程に示すように、上記ボール８を上記
キャピラリ１の下端に保持する。上記キャピラリ１は、
これ以後、以下に説明するように駆動されワイヤボンデ
ィング動作を行う。Next, a wire bonding process using the capillary 1 and the metal wire 2 will be described with reference to FIG.
This will be described with reference to FIGS. 2, 3 and 4. First, the capillary 1 is positioned facing above a predetermined electrode pad 5 (first bonding point) on the semiconductor chip 4 by operating an XY table (not shown). Then, the electric torch 9 is operated, and the tip portion of the metal wire 2 is melted by heating by electric discharge.
A spherical ball 8 is formed at the tip of the. When the ball 8 is formed, the capillary 1 is driven downward by a predetermined amount to hold the ball 8 at the lower end of the capillary 1 as shown in the process of FIG. The capillary 1 is
After that, the wire bonding operation is performed by driving as described below.

【００３１】前記図４（ｂ）および図４（ｃ）に示すよ
うに、キャピラリ１が点Ｂ（時刻ｔｂ）に達したなら
ば、キャピラリ１は超音波振動を開始する。このこと
で、上記キャピラリ１の下端に保持されたボール８は、
上記半導体チップ４の電極パッド５の押し付けられる前
から超音波域で振動することとなる。なお、前記キャピ
ラリ１の超音波振動の開始は、前記以外に、点Ａ（時刻
ｔａ）に達した時から予め開始してもよい。このキャピ
ラリ１は、点Ａ以後、緩やかに下降し、図４（ｃ）に示
す点Ｂで上記ボール８を上記半導体チップ４の電極パッ
ド５に当接させる。図１の工程に示すのが、このとき
の状態である。As shown in FIGS. 4 (b) and 4 (c), when the capillary 1 reaches the point B (time tb), the capillary 1 starts ultrasonic vibration. As a result, the ball 8 held at the lower end of the capillary 1 is
Before the electrode pad 5 of the semiconductor chip 4 is pressed, it vibrates in the ultrasonic range. In addition to the above, the ultrasonic vibration of the capillary 1 may be started in advance when the point A (time ta) is reached. The capillary 1 descends gently after the point A, and brings the ball 8 into contact with the electrode pad 5 of the semiconductor chip 4 at the point B shown in FIG. The state at this time is shown in the process of FIG.

【００３２】上記キャピラリ１は、この点Ｂ以後、ボー
ル８が図４（ａ）に示す圧力Ｐ１、及び図４（ｂ）に示
すキャピラリ１の振動振幅ＡＶ１で電極パッド５への押
し付けを開始する。その結果、図４（ｃ）時刻ｔｂ〜時
刻ｔ１で示す間ボール８が押し潰され、超音波による接
合を開始した後、上記キャピラリ１は若干量ではある
が、点Ｂから点Ｃまで下降する。そして、キャピラリ１
は、点Ｃの時刻ｔ１から時刻ｔ２まで圧力Ｐ１、振動振
幅ＡＶ１でボール８を電極パッド５に押圧する。この結
果、上記超音波振動により、ボール８は電極パッド５に
当接した中心の部位から接合されていく。After this point B, the capillary 1 starts pressing the ball 8 against the electrode pad 5 with the pressure P1 shown in FIG. 4A and the vibration amplitude AV1 of the capillary 1 shown in FIG. 4B. . As a result, the ball 8 is crushed during the period from time tb to time t1 in FIG. 4C, and after the ultrasonic bonding is started, the capillary 1 descends from the point B to the point C although the amount is a little. . And the capillary 1
Presses the ball 8 against the electrode pad 5 with pressure P1 and vibration amplitude AV1 from time t1 to time t2 at point C. As a result, due to the ultrasonic vibration, the ball 8 is joined from the central portion in contact with the electrode pad 5.

【００３３】図２（ａ）は、前記図１の工程（第１の
工程）におけるボンディング点における接合状態を拡大
して示す図である。図示するように、図４（ｃ）の時刻
ｔｂからｔ１で示す間、ボンディング位置接合表面と金
属ワイヤ２が接触して擦れ合ってスクイズアウト１２が
前記ボール８の周辺に発生する場合がある。上記ボール
８が電極パッド５に押し付けられ、接合が開始され、所
定時間の間（時刻ｔｂからｔ１で示す間、）小さい圧力
Ｐ１と大きな振動振幅ＡＶ１でボール８を電極パッド５
に押圧する。圧力Ｐ１が小さい結果、ボンディング位置
の接合面の接触面積が小さく、従ってボンディング位置
接合表面の傷が少なく、スクイズアウト１２の発生が少
ない。また、振動振幅ＡＶ１が大きい結果、ボンディン
グ位置接合表面と金属ワイヤ２が超音波振動により広範
囲のスクラブ動作が行なわれ、ボンディング表面とボン
ディングワイヤーとの接合面の異物を広範囲に除去でき
る。FIG. 2A is an enlarged view showing a bonding state at a bonding point in the step (first step) of FIG. As shown in the figure, during the period from the time tb to the time t1 in FIG. 4C, the squeeze-out 12 may occur around the ball 8 due to contact between the bonding position bonding surface and the metal wire 2 and rubbing against each other. The ball 8 is pressed against the electrode pad 5 to start the bonding, and the ball 8 is pressed against the electrode pad 5 with a small pressure P1 and a large vibration amplitude AV1 for a predetermined time (between time tb and t1).
Press on. As a result of the small pressure P1, the contact area of the bonding surface at the bonding position is small, and therefore the scratches on the bonding surface at the bonding position are small and the squeezeout 12 is less likely to occur. Further, as a result of the large vibration amplitude AV1, the bonding position bonding surface and the metal wire 2 are scrubbed in a wide range by ultrasonic vibration, and foreign matter on the bonding surface between the bonding surface and the bonding wire can be removed in a wide range.

【００３４】上記キャピラリ１は、点Ｄの時刻ｔ２から
時刻ｔ３まで圧力Ｐ２、振動振幅ＡＶ２でボール８を電
極パッド５に押圧する。前記図１の工程（第２の工
程）に示すのが、このときの状態である。なお、前記図
１の工程で示した圧力Ｐ２と振動振幅ＡＶ２と、前記
図１の工程で示した圧力Ｐ１と振動振幅ＡＶ１とは、
それぞれＰ２＞Ｐ１、ＡＶ２＜ＡＶ１の関係がある。圧
力Ｐ２が圧力Ｐ１に比べて大きい結果、図４（ｃ）時刻
ｔ２〜時刻ｔｃで示すボール８が押し潰される間、上記
キャピラリ１は若干量ではあるが、点Ｄから点Ｅまで下
降する。そして、キャピラリ１は、点Ｄの時刻ｔ２から
時刻ｔ３まで圧力Ｐ２、振動振幅ＡＶ２でボール８を電
極パッド５に押圧する。この結果、上記超音波振動によ
り、ボール８は電極パッド５に当接した周辺の部位まで
接合されていく。The capillary 1 presses the ball 8 against the electrode pad 5 with a pressure P2 and a vibration amplitude AV2 from time t2 at point D to time t3. The state at this time is shown in the step (second step) of FIG. The pressure P2 and the vibration amplitude AV2 shown in the process of FIG. 1 and the pressure P1 and the vibration amplitude AV1 shown in the process of FIG.
There is a relationship of P2> P1 and AV2 <AV1, respectively. As a result of the pressure P2 being larger than the pressure P1, while the ball 8 shown at time t2 to time tc in FIG. Then, the capillary 1 presses the ball 8 against the electrode pad 5 with the pressure P2 and the vibration amplitude AV2 from the time t2 at the point D to the time t3. As a result, due to the ultrasonic vibration, the ball 8 is joined to the peripheral portion in contact with the electrode pad 5.

【００３５】図４（ｃ）の時刻ｔ２からｔ３で示す間、
ボンディング位置接合表面と金属ワイヤ２が接触して、
圧力Ｐ２により上記電極パッド５との接触面積を次第に
広げていく。このように圧力が前記図１の工程で示し
た圧力Ｐ１より増加することにより、ボール８、電極パ
ッド５に接触した部位（中央部）から周辺部に向かって
順に上記超音波エネルギによってこの電極パッド５に接
合されていく。During the period from time t2 to t3 in FIG. 4 (c),
Bonding position The contact between the bonding surface and the metal wire 2,
The contact area with the electrode pad 5 is gradually expanded by the pressure P2. By increasing the pressure above the pressure P1 shown in the step of FIG. 1, the ultrasonic wave energy is applied to the electrode pad in order from the portion (center portion) in contact with the ball 8 and the electrode pad 5 toward the peripheral portion. It will be joined to 5.

【００３６】図３は、前記図１の工程（第２の工程）
での接合部の接合状態を説明する図である。図３（ａ）
は前記ボール８が電極パッド５に最終的に圧力Ｐ２で圧
着された時の圧着方向の断面図である。図３（ｂ）は、
図３（ａ）のボール８と電極パッド５の接合点における
断面における圧力分布を、図３（ｃ）は圧着方向のボー
ル８の圧力分布を、それぞれ説明する図である。FIG. 3 shows the process of FIG. 1 (second process).
It is a figure explaining the joining state of the joining part in FIG. Figure 3 (a)
FIG. 6 is a sectional view in the pressure bonding direction when the ball 8 is finally pressure bonded to the electrode pad 5 with pressure P2. Figure 3 (b) shows
3A is a diagram for explaining the pressure distribution in the cross section at the junction between the ball 8 and the electrode pad 5 of FIG. 3A, and FIG. 3C is a diagram for explaining the pressure distribution of the ball 8 in the pressure bonding direction.

【００３７】図３に示すように、ボール８と電極パッド
５の接合面において、ボール８は中心点部分８ｃの密着
力は第１の工程で大きな振動振幅ＡＶ１により表面に付
着した有機物、酸化物が取り除かれ、第２の工程での大
きな圧力Ｐ２で押圧される結果、密着力が高く、その周
辺８ａ、８ｂでの密着力は前記スクイズアウト１２を押
さえ込むために前記中心点部分８ｃの密着力より低くな
る。前述のように、第１の工程での圧力Ｐ１より大きい
第２の工程での圧力Ｐ２によりボール８が押し潰される
ことによって、前記第１の工程で発生した僅かなスクイ
ズアウト１２が図２（ｂ）に示すようにボール８の下部
周辺に押さえ込まれ、発生したスクイズアウト１２の周
囲への飛散が防止される。その結果、異物の除去工程及
び除去ツールを必要としない。As shown in FIG. 3, in the bonding surface of the ball 8 and the electrode pad 5, the adhesion force of the center point portion 8c of the ball 8 is the organic substance or oxide adhered to the surface by the large vibration amplitude AV1 in the first step. Are removed and pressed by the large pressure P2 in the second step, resulting in high adhesion, and the adhesion at the periphery 8a, 8b is the adhesion of the central point portion 8c for pressing down the squeezeout 12. Will be lower. As described above, the ball 8 is crushed by the pressure P2 in the second step, which is larger than the pressure P1 in the first step, so that the slight squeeze-out 12 generated in the first step is shown in FIG. As shown in b), the ball 8 is pressed down around the lower part of the ball 8 to prevent the generated squeeze-out 12 from scattering around. As a result, there is no need for a foreign matter removal step and removal tool.

【００３８】また、前記図１の工程における振動振幅
ＡＶ２は工程における振動振幅ＡＶ１よりも小さいこ
とから、たまたまボール８の下部周辺に押さえ込まれな
かったスクイズアウト１２の飛散も少なくて済む。更
に、振幅が減少することによって工程で圧着された接
合面が過大な振幅で振動されることがなくなり、既に密
着された中心部における密着度を低下することもない。
また、前記図１の工程における圧力Ｐ２は工程にお
ける圧力Ｐ１よりも大きいことから、中心における接合
面の密着度は、より強固になる。そして一定時間が経過
し、上記ボール８完全に接合されたならば、第２の工程
を終了し、上記キャピラリ１は超音波振動が停止され時
刻ｔ３から上昇駆動される。なお、前記キャピラリ１の
超音波振動の停止は、キャピラリ１が上昇駆動された後
に停止するようにしてもよい。Further, since the vibration amplitude AV2 in the step of FIG. 1 is smaller than the vibration amplitude AV1 in the step, the squeeze-out 12 which is not pressed down around the lower portion of the ball 8 is less likely to be scattered. Further, since the amplitude is reduced, the joining surface crimped in the process is not vibrated with an excessive amplitude, and the degree of adhesion at the already adhered central portion is not reduced.
Further, since the pressure P2 in the step of FIG. 1 is larger than the pressure P1 in the step, the adhesion of the joint surface at the center becomes stronger. Then, when the ball 8 is completely joined after a lapse of a certain time, the second step is ended, the ultrasonic vibration of the capillary 1 is stopped, and the capillary 1 is driven to rise from time t3. The ultrasonic vibration of the capillary 1 may be stopped after the capillary 1 is driven upward.

【００３９】上記キャピラリ１は図１の工程から図１
の工程に示すように、上記金属ワイヤ２を繰り出しつ
つ上昇駆動されると共に水平方向に駆動され、第２のボ
ンディング点であるプリント基板１０の電極パッド１１
上に対向位置決めされる。そして、上記キャピラリ１は
再び下降駆動され、上述した第１のボンディング点に対
する動作と同様の動作により、上記金属ワイヤ２を上記
プリント基板１０の電極パッド１１に押し付け、超音波
振動を印加することで接合を行っていく。この場合は、
上記第１のボンディング点の場合と異なり、金属ワイヤ
２自体を押し潰すことで、この金属ワイヤ２を接合す
る。この場合も、上記ワイヤ２の一部が上記電極パッド
１０に接触した時点から接合が開始され、図４（ａ）、
（ｂ）、（ｃ）に示すように圧力と振動振幅とを切り替
える第１工程、第２工程を有するようにしても良く、ま
たは、前記第１工程、又は第２工程のみであってもよ
い。The above-mentioned capillary 1 is formed from the process of FIG.
As shown in the process (1), the metal wire 2 is raised and driven in the horizontal direction while being fed out, and the electrode pad 11 of the printed circuit board 10, which is the second bonding point, is driven.
Positioned opposite to above. Then, the capillary 1 is driven down again, and the metal wire 2 is pressed against the electrode pad 11 of the printed circuit board 10 by the same operation as the operation for the first bonding point described above, and ultrasonic vibration is applied. Joining is done. in this case,
Unlike the case of the first bonding point, the metal wire 2 is joined by crushing the metal wire 2 itself. Also in this case, the bonding is started from the time when a part of the wire 2 comes into contact with the electrode pad 10, and as shown in FIG.
As shown in (b) and (c), there may be provided a first step and a second step for switching the pressure and the vibration amplitude, or only the first step or the second step. .

【００４０】図１の工程の後に、工程において、上
記ワイヤクランパ７を作動させ上記金属ワイヤ２を保持
した後、キャピラリ１およびワイヤクランパ７を上昇さ
せることで前記金属ワイヤ２を上方に引上げる。このこ
とで図１の工程に示すように、金属ワイヤ２は、接合
された部位の直上で切断される。金属ワイヤ２が最初に
キャピリ１に通された時以降、図１の工程の後に、工
程で述べたのと同様にして、工程では、電気トーチ
９が作動し、放電による加熱により上記金属ワイヤ２の
先端部を溶融させ、この金属ワイヤ２の先端部に球状の
ボール８を形成する。そして、新たなボール８が形成さ
れたならば図１の工程に戻り、他の接合部の接合が同
様にしてなされる。なお、かかる場合、図１の工程で
のボールの形成工程は省略する。After the step of FIG. 1, in the step, the wire clamper 7 is operated to hold the metal wire 2, and then the capillary 1 and the wire clamper 7 are raised to pull the metal wire 2 upward. As a result, as shown in the process of FIG. 1, the metal wire 2 is cut immediately above the joined portion. After the metal wire 2 is first passed through the capillary 1, after the step of FIG. 1, the electric torch 9 is operated in the same manner as described in the step, and the metal wire 2 is heated by electric discharge. The tip of the metal wire 2 is melted to form a spherical ball 8 at the tip of the metal wire 2. Then, when a new ball 8 is formed, the process returns to the step of FIG. 1 and the other joints are joined in the same manner. In this case, the ball forming process in the process of FIG. 1 is omitted.

【００４１】[0041]

【発明の効果】以上述べたように、この発明は、ボンデ
ィング工程に金属ワイヤの圧力と振動振幅をそれぞれ制
御する工程を設けたワイヤボンディング方法である。即
ち、半導体チップの電極パッドと前記半導体チップを載
置するリードフレームのインナーリード部とを金属ワイ
ヤを用いて接続するワイヤボンディング方法において、
ボンディング位置の接合表面にボンディング用のツール
を所定の圧力で接触させて金属ワイヤを所定の振幅で振
動させて金属ワイヤを押圧する第１工程と、該第１工程
の後に前記第１の工程より大きい圧力で前記金属ワイヤ
を押圧する第２工程とを有することを特徴とする。As described above, the present invention is a wire bonding method in which a step of controlling the pressure and vibration amplitude of a metal wire is provided in the bonding step. That is, in the wire bonding method of connecting the electrode pad of the semiconductor chip and the inner lead portion of the lead frame on which the semiconductor chip is mounted by using a metal wire,
A first step of pressing a metal wire by bringing a bonding tool into contact with a bonding surface at a bonding position at a predetermined pressure to vibrate the metal wire at a predetermined amplitude, and from the first step after the first step. A second step of pressing the metal wire with a large pressure.

【００４２】このように圧力を変化する２つの工程を設
けて、圧力Ｐ１より大きい圧力Ｐ２によりボール８が押
し潰されることによって、第１の工程で発生した僅かな
スクイズアウト１２がボール８の下部周辺に押さえ込ま
れ、発生したスクイズアウト１２の周囲への飛散が防止
され、半導体素子の信頼性を向上する効果がある。ま
た、その結果、異物の除去工程及び除去ツールを必要と
せず、装置の低価格化に寄与する効果もある。By providing the two steps for changing the pressure in this way, and the ball 8 is crushed by the pressure P2 larger than the pressure P1, the slight squeeze-out 12 generated in the first step causes the slight squeezeout 12 to occur in the lower portion of the ball 8. The squeezeout 12 that is pressed down to the periphery is prevented from scattering around and the reliability of the semiconductor element is improved. In addition, as a result, there is no need for a step of removing foreign matter and a removal tool, which also contributes to cost reduction of the apparatus.

【００４３】また、前記第２の工程における振動振幅Ａ
Ｖ２は、前記第１の工程における振動振幅ＡＶ１よりも
小さいことから、たまたまボール８の下部周辺に押さえ
込まれなかったスクイズアウト１２の飛散も少なくて済
み、半導体素子の信頼性を向上する効果がある。Further, the vibration amplitude A in the second step
Since V2 is smaller than the vibration amplitude AV1 in the first step, scattering of the squeeze-out 12 which is not pressed down around the lower portion of the ball 8 by chance is small, and the reliability of the semiconductor element is improved. .

【００４４】更に、前記第１の工程における振動振幅Ａ
Ｖ１よりも第２の工程における振動振幅ＡＶ２が減少す
ることによって前記第１の工程で圧着された接合面が過
大な振幅で振動されることがなくなり、既に密着された
中心部における密着度を低下することもなく、同様にし
て半導体素子の信頼性を向上する効果を有する。更にま
た、前記第２の工程における圧力Ｐ２は前記第１の工程
における圧力Ｐ１よりも大きいことから、中心における
接合面の密着度は、より強固になる効果がある。Further, the vibration amplitude A in the first step
Since the vibration amplitude AV2 in the second step is smaller than V1, the joining surface crimped in the first step is not vibrated with an excessive amplitude, and the degree of adhesion in the already adhered central portion is reduced. Similarly, it has the effect of improving the reliability of the semiconductor element. Furthermore, since the pressure P2 in the second step is larger than the pressure P1 in the first step, there is an effect that the degree of adhesion of the joint surface at the center becomes stronger.

【００４５】又、振動振幅の変化は、超音波振動子駆動
装置により該超音波振動子に印加する印加電圧を切り替
えて行なうことにより簡単にボンディング工程の制御が
できる。以上述べたように、本発明では、従来の超音波
振動式のボンディング方法では得られなかった、超音波
振動式の接合時に発生するスクイズアウトなどの異物の
発生を抑制、発生した前記異物の飛散を防止、接合点の
密着度の向上が可能になり、この方法により製造された
半導体の信頼性を向上できると共に、合わせて装置の低
減化を可能にすることができる。Further, the change of the vibration amplitude can be easily controlled by switching the applied voltage applied to the ultrasonic vibrator by the ultrasonic vibrator driving device. As described above, in the present invention, the generation of foreign matter such as squeeze out that occurs during ultrasonic vibration type bonding, which cannot be obtained by the conventional ultrasonic vibration type bonding method, is suppressed, and the generated foreign matter scatters. It is possible to improve the reliability of the semiconductor manufactured by this method, and also to reduce the number of devices.

【図面の簡単な説明】[Brief description of drawings]

【図１】ワイヤボンディング方法の工程を示す概略工程
図であって、その工程は、符号乃至に示す順序であ
る。FIG. 1 is a schematic process diagram showing the steps of a wire bonding method, which steps are in the order shown by reference numerals.

【図２】図１の工程及びにおけるボンディング点に
おける接合状態を拡大して示す図であって、図２
（ａ）、図２（ｂ）は、それぞれ図１の工程工程及び
に対応した図である。2 is an enlarged view showing a bonding state at a bonding point in the step of FIG. 1 and FIG.
FIG. 2A and FIG. 2B are views corresponding to the process steps of FIG.

【図３】接合部の接合状態を説明する図であって、図３
（ａ）は前記ボールが電極パッドに圧着された時の圧着
方向の断面図である。図３（ｂ）は、図３（ａ）のボー
ルと電極パッドの接合点における断面における圧力分布
を、図３（ｃ）は圧着方向のボールの圧力分布を、それ
ぞれ説明する図である。FIG. 3 is a diagram for explaining a joined state of a joined portion, and FIG.
FIG. 7A is a sectional view in the pressure bonding direction when the ball is pressure bonded to the electrode pad. 3B is a diagram for explaining the pressure distribution in the cross section at the junction between the ball and the electrode pad of FIG. 3A, and FIG. 3C is a diagram for explaining the pressure distribution of the ball in the pressure bonding direction.

【図４】キャピラリの加圧制御および超音波振動の振幅
制御を示す図であって、図４（ａ）、図４（ｂ）、図４
（ｃ）は、それぞれ加圧制御と振幅制御及びキャピラリ
の位置を示す図である。FIG. 4 is a diagram showing pressure control of the capillaries and amplitude control of ultrasonic vibrations, and FIG. 4 (a), FIG. 4 (b), and FIG.
(C) is a figure which shows pressurization control, amplitude control, and the position of a capillary, respectively.

【図５】従来のワイヤボンディング装置の説明図であ
る。FIG. 5 is an explanatory diagram of a conventional wire bonding device.

【図６】図６はキャピラリの動作を説明する図であっ
て、図６（ａ）は、キャピラリの上下方向の動作を時間
との関係で示す図、図６（ｂ）は、ゲイン切替により発
生する超音波振動の振幅を示す図、図６（ｃ）は、キャ
ピラリに振動を与える、超音波振動子に対する電圧印加
のゲイン切替を示す図である。FIG. 6 is a diagram for explaining the operation of the capillary, FIG. 6 (a) is a diagram showing the vertical operation of the capillary in relation to time, and FIG. FIG. 6C is a diagram showing the amplitude of the ultrasonic vibration generated, and FIG. 6C is a diagram showing the gain switching of the voltage application to the ultrasonic vibrator, which gives the capillary vibration.

【図７】各種のボンディング方法における接合部の接合
状態を説明する図であって、図７（ａ）はボールが電極
パッドに圧着された時の圧着方向の断面図、図７（ｂ）
と図７（ｃ）は、それぞれボールと電極パッドの接合点
における、ボールへの圧力分布を説明する図である。7A and 7B are views for explaining a bonding state of a bonding portion in various bonding methods, FIG. 7A is a sectional view in a pressure bonding direction when a ball is pressure bonded to an electrode pad, and FIG.
FIG. 7C is a diagram for explaining the pressure distribution on the ball at the junction between the ball and the electrode pad.

【符号の説明】[Explanation of symbols]

１ キャピラリ ２ 金属ワイヤ ４ 半導体チップ ５ 電極パッド ６ インナーリード部 ７ クランパ ８ ボール ９ 電気トーチ １０ プリント基板 １１ 電極パッド１１ １２ スクイズアウト 1 capillary 2 metal wire 4 semiconductor chips 5 electrode pads 6 Inner lead part 7 clamper 8 balls 9 electric torch 10 printed circuit boards 11 electrode pad 11 12 Squeeze out

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】半導体チップの電極パッドと前記半導体チ
ップを載置するリードフレームのインナーリード部とを
金属ワイヤを用いて接続するワイヤボンディング方法に
おいて、ボンディング位置の接合表面にボンディング用
のツールを所定の圧力で接触させて金属ワイヤを所定の
振幅で振動させて金属ワイヤを押圧する第１工程と、該
第１工程の後に前記第１の工程より大きい圧力で前記金
属ワイヤを押圧する第２工程とを有することを特徴とす
るワイヤボンディング方法。1. In a wire bonding method for connecting an electrode pad of a semiconductor chip and an inner lead portion of a lead frame on which the semiconductor chip is mounted by using a metal wire, a bonding tool is predetermined on a bonding surface at a bonding position. Step of pressing the metal wire by vibrating the metal wire at a predetermined amplitude by contacting the metal wire with a predetermined pressure, and a second step of pressing the metal wire with a pressure higher than the first step after the first step A wire bonding method comprising: 【請求項２】前記第２工程における金属ワイヤの振動振
幅を、前記第１工程における金属ワイヤの振動振幅より
小さくすることを特徴とする請求項１に記載のワイヤボ
ンディング方法。2. The wire bonding method according to claim 1, wherein the vibration amplitude of the metal wire in the second step is smaller than the vibration amplitude of the metal wire in the first step. 【請求項３】前記金属ワイヤの振動振幅の変化は、超音
波振動子駆動装置により前記超音波振動子に印加する印
加電圧を切り替えてボンディング用のツールを振動する
ことを特徴とする請求項１に記載のワイヤボンディング
方法。3. The change in the vibration amplitude of the metal wire causes the bonding tool to vibrate by switching the applied voltage applied to the ultrasonic vibrator by the ultrasonic vibrator driving device. The wire bonding method described in.
JP2002057597A 2002-03-04 2002-03-04 Method for wire bonding Pending JP2003258042A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002057597A JP2003258042A (en) 2002-03-04 2002-03-04 Method for wire bonding

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002057597A JP2003258042A (en) 2002-03-04 2002-03-04 Method for wire bonding

Publications (1)

Publication Number Publication Date
JP2003258042A true JP2003258042A (en) 2003-09-12

Family

ID=28667818

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002057597A Pending JP2003258042A (en) 2002-03-04 2002-03-04 Method for wire bonding

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Country Link
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006156795A (en) * 2004-11-30 2006-06-15 Toyota Motor Corp Method of joining semiconductor device
CN102723319A (en) * 2012-07-13 2012-10-10 日月光半导体制造股份有限公司 Semiconductor wire bonding structure and method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006156795A (en) * 2004-11-30 2006-06-15 Toyota Motor Corp Method of joining semiconductor device
JP4656921B2 (en) * 2004-11-30 2011-03-23 トヨタ自動車株式会社 Semiconductor element bonding method
CN102723319A (en) * 2012-07-13 2012-10-10 日月光半导体制造股份有限公司 Semiconductor wire bonding structure and method
CN105957852A (en) * 2012-07-13 2016-09-21 日月光半导体制造股份有限公司 Semiconductor wire bonding structure and method

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